This invention relates to wetness indicators used with absorbent products such as disposable diapers and the like.
A number of wetness indicators has been disclosed in the prior art for use on absorbent pad assemblies such as disposable diapers. With the development of increasingly improved materials to absorb and direct wetness away from the baby's body and into the absorbent layers of a diaper, it has become increasingly difficult for a parent to be able to tell when a diaper is wet by touching the interior diaper surface. Due to the improved absorbent layers, parents often allow an infant to completely saturate a diaper before changing the diaper. As a result, a period of time sufficient for bacteria to grow often elapses, and diaper rash often ensues. Therefore, it would be highly desirable to provide a disposable diaper having a wetness indicator which immediately signals wetness within the absorbent layers.
A number of differing compositions or methods of construction has been suggested for indicating that a diaper is wet. For instance, U.S. Pat. No. 4,231,370 to Mroz et al. discloses a pH change/color change wetness indicator which is a solid mixture dispersed in an adhesive. U.S. Pat. No. 4,022,211 to Timmons et al. discloses a water soluble coloring agent which is visible when the diaper is dry, but which disappears when the diaper becomes wet. U.S. Pat. No. 3,952,746 to Summers discloses the use of humidity indicator paper mounted on an absorbent area of the diaper. U.S. Pat. No. 4,327,731 to Powell discloses moisture activated enzymatic systems and chromogens or pigment producing agents used as wetness detectors. U.S. Pat. Nos. 3,759,261 to Wang and 4,192,311 to Felfoldi disclose masked color layers which become visible when intervening layers become wet.
It is unnecessary for a diaper wetness indicator to indicate pH. Many pH indicators have proven to be unreliable. Multi-layered masking systems prove to be somewhat ineffective. An inexpensive, non-toxic, simple composition signalling the presence of water as a wetness indicator would be advantageous.